Non-metal electric heating system and method, and tankless water heater using the same

ABSTRACT

A tankless heater includes at least one non-metallic tube, at least one heating layer on or adjacent an external or internal surface of the tube, and a controller to generate a signal to be applied to the heating layer. The signal from the controller is applied through one or more electrodes coupled to the heating layer, and the heating layer generates heat in response to the signal. The heat is then transferred to a liquid flowing through, a gel located within, or a solid inside of the tube to heat the liquid, gel, or solid to certain temperature range, which may or may not be predetermined. Or, the heat is transferred to a liquid, a gel or a solid around the tube to heat the liquid, gel or solid to certain temperature, which may or may not be predetermined. In a multiple-tube configuration, the tubes may be independently selected and may have different temperature ranges. Also, according to one arrangement, no heating element is included inside any of the tubes.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority under 35 USC §119(e) to provisionalU.S. Patent Application Ser. No. 61/223,962, filed on Jul. 8, 2010, thecontent of which is incorporated herein by reference.

BACKGROUND

1. Field

One or more embodiments disclosed herein relate to heaters.

2. Background

Tankless water heaters have been developed in recent years and are knownby a variety of names, including instantaneous, combination or “combi”boilers, continuous flow, inline, flash, or on-demand water heaters.This type of water heater is gaining in popularity mainly forspace-saving and energy efficiency reasons. These advantages areachieved by heating water as it flows through the unit|_([S1]).

As a practical matter, tankless water heaters may be installedthroughout a household at various points-of-use (POU) or at acentralized location. They also can be used alone or in combination witha centrally located water heater. In some cases, larger tankless modelsmay be used to provide the hot water requirements for an entire house.Whether installed at one or multiple POUs, tankless water heatersprovide a continuous flow of hot water and energy savings compared withtank-type heaters, which are only able to provide a finite supply of hotwater limited by tank size and hot water recovery rates.

For all of the advantages they provide, tankless water heaters on themarket today suffer from significant disadvantages. First, there is adelay between when water flow starts and when a flow detector activatesone or more heating elements. This causes cold water to flow before hotwater. The flow of cold water under these circumstances is undesirableand is particularly noticeable when a hot water faucet is repeatedlyturned on and off by a user.

Second, when activated, tankless water heaters tend to heat idle waterin surrounding pipes through the process of convection. Also, tanklesswater heaters only heat water upon demand so that idle water in thepiping is cold. Thus, there is a more apparent “flow delay” for hotwater to reach a distant faucet.

Third, because tankless water heaters are inactive when hot water is notbeing used, they may be incompatible with hot water recirculationsystems unless an expansion tank is added.

Fourth, tankless water heaters often have minimum flow requirementsbefore the heater is activated. This can create in a gap between thetemperature of cold water and the coolest warm temperature that can beachieved with a hot-and-cold water mix. This gap can produce undesirableeffects to the user.

Moreover, unlike tank-type heaters, the hot water temperature from aconventional tankless water heater is inversely proportional to the rateof water flow. In other words, the faster the flow, the less time waterspends in the heating element. As a result, a certain range of desirablehot water temperatures may not be achievable or achieving a desiredtemperature with precision may be difficult to control. For example, incertain situations mixing hot and cold water to just the “right”temperature using a single-lever faucet (e.g., while taking a shower)may take a lot of practice to master. A user may therefore considerinstalling a temperature compensating valve under these circumstances,which can increase costs.

In addition to the foregoing disadvantages, installing a conventionaltankless water heating system may be expensive, particularly inretro-fit applications. Also, tankless heaters have demonstrated certaininefficiencies and safety problems that need improvement.

Tankless and other forms of water heaters are also disadvantageous interms of their metallic heating elements. These elements tend to corrodeover time, thereby necessitating their replacement over relatively shortperiods of time. This can be especially burdensome to homeowners interms of cost and convenience. Also, conventional water heaters that usemetallic heating elements have proven to be inefficient, unmanageable,or both, for many applications.

In view of the foregoing considerations, there is a need in the art fora more efficient and effective heating system and method capable, forexample, of not only heating water more quickly than conventionalsystems and methods but also with greater efficiency, precision, andsafety. A need also exists for a heating system and method of theaforementioned type which is more durable, longer-lasting, andcost-efficient compared with those that use metallic heating elements.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A shows one embodiment of a non-metallic heating element, and FIG.1B shows a cross-section of the element in FIG. 1A.

FIG. 2 shows one embodiment of a tankless water heater that uses one ormore non-metallic heating elements such as shown in FIGS. 1A and 1B.

FIG. 3 shows a second embodiment of a tankless water heater.

FIG. 4 shows a third embodiment of a tankless water heater

DETAILED DESCRIPTION

One or more embodiments herein are directed to systems and methods forinstantaneously generating heat in any one of a variety of residential,commercial, industrial, or medical applications. The heat is generatedusing one or more non-metallic heating elements which prove to be safer,more efficient, and more cost effective than their metallic counterpartsover the lifetime of the equipment.

According to one illustrative application, the heating system and methodmay be applied to heating water, for example, for a user's faucet,shower, appliance, or other device. In another application, the liquidsdifferent from water such as a gel may be heated. In still anotherapplication, the air or a solid may be heated. Moreover, becausenon-metallic heating elements are used, the embodiments disclosed hereinrequire less power due to no efficiency or capacity decay, making themsuitable for use in virtually any application that requires heat. Othertypes of metallic heating elements may build up lime scale over time,which reduces heating elements ability to heat water.

FIG. 1A shows one embodiment of a heating element having an electricheating layer 1 disposed on a non-metallic tube 2. The heating layer maybe in the form of a coating, film, or layer which generates heat when avoltage or other electrical signal is applied. The coating, film, orlayer may be applied directly to the exterior surface of the tube or aninterior surface of non-metallic tube. Such a coating, film, or layermay be made from electric heating membrane material agglutinated onto orembedded or burned into the exterior or interior surface of thenon-metallic tube or otherwise applied to the tube surface. Examples ofthis material include carbon fiber, nylon, conductive polyimides,conductive indium-tin-oxide (ITO), kapton, and polymer thick-film inksthat are screen printed onto a substrate.

When a signal is applied to this material by electrodes 3 and 4, heat isgenerated based on electrical resistance. The heat passes through thetube wall to heat a medium disposed therein to a desired temperature.For many residential applications, a temperature of between 20° C. and100° C. may be sufficient. For other, commercial applications, a rangeof between 20° C. and 500° C. may be more suitable.

The medium inside the tube to be heated may be air or another gas, wateror another liquid, gel, or even a solid. The size and quantity ofelectric heating material and the amount of voltage applied thereto (aswell as other electrical properties such as frequency) may be varied orset to generate a predetermined amount of heat (e.g., temperature)and/or heating response time for the intended application.

FIG. 1B shows a sectional view of the heating element in FIG. 1A. Inthis view, the medium 5 is shown as water passing through the tube at apredetermined rate. Because the heating layer is able to provideinstantaneous heating, the water is immediately heated as a result ofthe signal applied through the electrodes. As a safety precaution,insulating material (not shown) may be mounted proximate the heatinglayer.

The non-metallic tube 1 may be made of quartz, glass, or ceramic oranother material capable of withstanding heat. The use of a non-metallictube is highly desirable for many applications in order to preventcorrosion which occurs in more traditional heaters that use metallicheating elements. The thickness of the tube walls is preferably set tobe strong enough to withstand breakage as a result of shock or othersudden forces, but thin enough to rapidly transfer heat from the heatinglayer to medium 5. The thickness range may, for example, lie in therange of between 5 to 10 mm for many applications. Of course, in otherapplications, a different thickness range may be used.

The electrodes 4 and 5 may be attached to the heating layer using anyone of a variety of connections including but not limited to lead wires,conductive terminals, and metallic traces. The signal generatorconnected to the electrodes generates signals at a predeterminedvoltage, frequency, and/or current to heat the medium inside the tube tothe intended temperature, or temperature range.

FIG. 2 shows one embodiment of a tankless water heater which uses one ormore heating tubes such as shown in FIGS. 1A and 1B. The tankless waterheater includes a heating section 10, a power source 11, one or moresets of terminals 12, and a controller 13, all of which are supportedwithin a housing 20. The power source may include a transformer forproviding power to the controller, and the terminals are coupled totransfer the signals generated by the controller to the heating sectionat a predetermined voltage, current, and/or frequency set based on theoperational requirements of the heater and the temperature to beachieved by application of the heat.

The heating section contains a predetermined number of heating tubes forheating water. In this illustrative embodiment, two heating tubes 40 and50 are used to provide heated water, for example, to differentappliances in a house. A different number of tubes may be used in otherembodiments.

The heating tubes are held between upper and lower mounting sections 21and 22 in a fixed position. The mounting sections not only providestructural support for the tubes, but also include a water path betweenthe tubes or electrodes for electrically connecting the heating layersof the tubes to different sets of terminals 12.

To help secure the tubes between the mounting sections, one or moresupport rods 23 are provided adjacent the tubes. Also, a number ofsealing components are provided to seal the tubes from leaks, both alongtheir lengths and also at the interface points. The sealing componentsmay, for example, be made of a pressurized silicon polymer or othersuitable sealing material sustainable to, for example, over 3.0 MPawater pressure.

The heating tubes are coupled to different water pipes. In this two-tubeconfiguration, tube 40 is coupled to an inlet water pipe 41 and tube 50is coupled to inlet water pipe 51. Water passing through tubes 40 and 50then exit through exit pipes 42 and 52, respectively. The exit pipescarry the water to different destinations that have heating demands,e.g., dishwasher and clothes washer. As mentioned, the interface pointsbetween the heating tubes and their corresponding inlet and outlet pipesare provided with sealing members to protect against leaks. The sealingmembers may be made from nylon or another polymer-based material.

The controller 13 generates signals at one or more predeterminedvoltages, currents, and/or frequencies to the heating layers of thetubes. The signals are applied to the electrodes of the tubes throughthe different sets of terminals 12. If the heating tubes are to heatwater to different temperatures, then the controller signals will beproportionately different.

Moreover, in a multiple-tube configuration such as shown in FIG. 2, thetubes may be identically made or may be different. If different, theheating layer on the tubes may be different to provide different heatingtemperature ranges. For example, one tube may heat water to a firsttemperature range suitable for one type of appliance or faucet, and theother tube may heat water to a second temperature range greater than thefirst temperature range suitable for another type of appliance orapplication. This two-temperature range configuration of the tanklesswater heater may be especially desirable for commercial applicationswhere heated water in vastly different temperature ranges (e.g., a firstrange of 20° C. to 100° C. and a second range of 20° C. to 500° C. maybe required).

In addition to the foregoing features, insulation may be provided atvarious points within the heating section 10 to protect the componentstherein. This insulation may be especially desirable at a locationbetween the tubes, to prevent a high-temperature range tube fromadversely affecting a low-temperature range tube. Insulation may also beprovided between the tubes and interior walls of the heating section.

Additional electrical components may be provided, for example, in theform of relays and/or timers to control the timing of when heated wateris to be supplied, optionally, a silicon-controlled rectifier to controlpower and voltage requirements of the heating section, flow sensors todetect the rate of water flow at various positions relative to theheating tubes, a temperature sensor to form part of a protection circuitto prevent overheating, power regulators, water leakage protectioncircuits to detect water escaping from the tubes and/or heating sectionhousing, and dry heat protection circuits. A ground for the electricalcircuits may be provided, for example, in the form of a connection toone or more of the inlet or outlet water pipes.

In addition, a heating element box or other means of protection may alsobe included to protect the heating elements from physical damage.Thermal insulation material may enhance the thermo efficiency of theequipment. These features may also protect the heating elements frombeing exposed when the unit is opened.

A control board box may be included to protect the control boards orcircuits used for the heating tubes, for example, by preventing ahigh-voltage section of the system from being exposed when the unit isopened.

An outside jack may be included to meet visual design requirements. Thecontroller 13 and other circuits may also be equipped with or interfacedto one or more control panels and/or buttons to allow a user to adjustpower, temperature, and/or other settings relating to heating. Thecontroller may modify the signals (e.g., voltage, current, or frequency)applied to the heating layer(s) of the tube(s) in accordance with theadjustments made through the control panel or buttons.

The embodiments of the non-metal water heater described herein may haveone or more of the following advantages. The non-metal tubes have highersustainability to voltage than metal heating elements. Also, thenon-metal tubes do not scale, have excellent insulation properties andtherefore are safer. The tubes also will not age for over many years,have a pure resistance load, heat up quickly, have high thermoefficiency, and long lifetime.

In addition, the non-metallic heating element of the tubes in anelectric water heater application demonstrate resistance to corrosionand are expected to have reduced power requirements and improvedoperational stability compared with their metallic counterparts.

FIG. 3 shows another embodiment of a tankless water heater which has asingle heating tube 150 in a substantially U-shaped configuration. Inthis embodiment, different sections 160 and 170 of the tube are used toheat water from inlet pipe 180 before being discharged through outletpipe 190. Using this two-section, single-tube configuration, water fromthe inlet pipe may be heated for a longer period of time. Moreover, thedifferent tubes may be individually controlled based on signals from thecontroller to effect heating at different stages and/or at differenttemperatures.

In other embodiments, a different number of heating tubes may be usedfrom the tubes shown in FIGS. 2 and 3. Varying the number of heatingtubes may have the effect of varying power capacity of the heatingelements. Depending on the capacity required for a particularapplication, three or more heating tubes may be group together forpurposes of generating heated water for discharge through a same ordifferent outlet pipes. Also, the multiple heating tubes may beselectively and independently activated in order to satisfy heatingrequirements for a particular application.

FIG. 4 shows another embodiment of a tankless water heater which usesmultiple heating tubes 210 and 220 to heat water from a single inletpipe 230. The heated water is then combined and passed through a singleoutlet pipe 240. In this embodiment, the heating tubes are independentlyand selectively activated based on signals from the controller tomeeting different heating requirements.

For example, the controller may supply signals to only heating tube 210to heat the water to within a low-temperature range. In this case,signals are not supplied to heating tube 220. The controller may thensupply signals to both heating tubes 210 and 220, to thereby activateboth tubes to heat the water to within a high-temperature range. If theheating tubes have different heating material or heating capabilities,the controller may supply signals to only heating tube 220 to heat thewater to a middle temperature range.

When the water is to be heated using only one tube, a three-wayelectronically controlled valve 240 may be located downstream of aninlet of the inlet pipe to shut off flow of water to a tube when theother tube is only to be selected for heating. Signals for controllingthe configuration of the valve may be generated from the controller.

In accordance with another embodiment, a water heating system which usesa tank to hold a supply of water may be provided. This system may useone or more non-metallic heating tubes disposed within the tank to heatthe supply of water. Alternatively, one or more inlet pipes aspreviously discussed may carry a flow of water stored in the tank to oneor more heating tubes with or without a water pump. Such a system may,thus, correspond to a tank-based water heating system where the heatingelements are located outside of the tank.

In accordance with any one of the aforementioned embodiments, one ormore intervening layers may be included between heating layer 1 andnon-metallic tube 2. These layers may include, for example, aninsulating layer, a sensing layer, a protective layer, an electrodelayer or any combination thereof.

In addition, one or more layers may be formed over heating layer 1including, for example, an insulating layer to prevent the heatgenerated by the heating layer from dissipating or escaping, a heatreflective layer to focus and/or redirect heating generated by layer 1towards the tube to provide improved transfer of heat, a protectivelayer to prevent against damage from outside forces and/or to preventthe heat generated for one tube from migrating to another adjacent tube.

Also, in the foregoing embodiments which use multiple tubes, the tubesare shown to be substantially parallel to one another. However, in otherembodiments, the tubes may, for example, be independently selected andperpendicular or otherwise angled relative to one another to meet theneeds of a particular application and/or inlet pipe/outlet pipeconfiguration.

In accordance with another embodiment, a heating system using one ormore non-metallic tubes may be provided to heat a gelatin-type material.The heated gelatin (as well as the water or liquids heated by the otherembodiments described herein) may be used for a variety of home,commercial, industrial, or medical uses. Alternatively, blood,chemicals, or other substances may be heated in other embodiments.

In accordance with one or more embodiments described herein, all theheating elements of the heating tubes are located outside of the tube,e.g., on or adjacent an external surface of each tube. None of theheating elements are included inside the tube. This is beneficial inthat if heating elements were included inside the tubes, then thoseelements over time would corrode or otherwise require replacement,thereby limiting the useful life of the entire system or increasing themaintenance costs thereof. In an alternative embodiment, a heatingelement may be included inside of the tube to provide extra heating ifnecessary.

Any reference to “one embodiment,” “an embodiment,” “exampleembodiment,” etc., means that a particular feature, structure, orcharacteristic described in connection with the embodiment is includedin at least one embodiment of the invention. The appearances of suchphrases in various places in the specification are not necessarily allreferring to the same embodiment. Further, when a particular feature,structure, or characteristic is described in connection with anyembodiment, it is submitted that it is within the purview of one skilledin the art to effect such feature, structure, or characteristic inconnection with other ones of the embodiments. Moreover, the features ofany one embodiment may be combined with the features of the otherembodiments.

Although embodiments have been described with reference to a number ofillustrative embodiments thereof, it should be understood that numerousother modifications and embodiments can be devised by those skilled inthe art that will fall within the spirit and scope of the principles ofthis disclosure. More particularly, various variations and modificationsare possible in the component parts and/or arrangements of the subjectcombination arrangement within the scope of the disclosure, the drawingsand the appended claims. In addition to variations and modifications inthe component parts and/or arrangements, alternative uses will also beapparent to those skilled in the art.

1. A tankless heater comprising: at least one non-metallic tube; atleast one heating layer on or adjacent the tube; and a controller togenerate a signal to be applied to the heating layer, wherein: thesignal is applied through electrodes coupled to the heating layer, theheating layer generates heat in response to the signal, said heattransferred to a liquid flowing through or around the tube to heat theliquid to within a first temperature range, and the heating layer is onor adjacent an external or internal surface of the non-metallic tube andno heating element is included on another surface of the non-metallictube in contact with the liquid.
 2. The tankless heater of claim 1,wherein the non-metallic tube is made of a material that includes atleast one of quartz, glass, ceramic, polymer or a synthetic material. 3.The tankless heater of claim 1, wherein the heating layer includes acoating applied to the external or interior surface of the tube.
 4. Thetankless heater of claim 3, wherein the film is made of a conductivematerial.
 5. The tankless heater of claim 4, wherein the film is madefrom conductive polyimides, conductive indium-tin-oxide (ITO), tinoxide, kapton, polymer inks or a combination thereof.
 6. The tank lessheater of claim 1, wherein the liquid is water, chemicals, blood, orgelatins.
 7. The tankless heater of claim 1, wherein the controlleradjusts the signal to change a temperature of the liquid based oncontrol information generated from a control panel, buttons, sensors, ora combination thereof.
 8. The tankless heater of claim 1, wherein thenon-metallic tube has: a first section including a first heating layer,a second section including a second heating layer, and a third sectionbetween the first and second section, wherein the second section isoriented in a direction different from at least one of the first orthird sections.
 9. The tankless heater of claim 8, wherein the secondsection does not include a heating layer.
 10. The tankless heater ofclaim 8, wherein the first section and third section are substantiallyparallel and the second section is substantially perpendicular to thefirst section and third section.
 11. The tankless heater of claim 1,further comprising: a plurality of non-metallic tubes; and a pluralityof heating layers on or adjacent respective ones of the tubes, whereinthe controller independently selects different combinations of thenon-metallic tubes based on signals applied to electrodes attached torespective ones of the non-metallic tubes.
 12. The tankless heater ofclaim 11, wherein: the heating layers on or adjacent the tubes are madeof different materials, and the tubes heat liquid to within differenttemperature ranges based on said different materials.
 13. The tanklessheater of claim 11, wherein: the controller generates different signalsfor respective ones of the tubes, said different signals causing thetubes to heat liquid to within different temperature ranges.
 14. Thetankless heater of claim 11, wherein the controller selects one of thenon-metallic tubes by sending a signal to said one tube and does notselect another one of the tubes by not sending a signal to the tube. 15.The tankless heater of claim 11, wherein the plurality of non-metallictubes are coupled to different inlet pipes.
 16. The tankless heater ofclaim 15, wherein the plurality of non-metallic tubes are coupled todifferent outlet pipes to provide heated water to differentdestinations.
 17. The tankless heater of claim 15, wherein the pluralityof non-metallic tubes are coupled to a same outlet pipe.
 18. Thetankless heater of claim 15, wherein: the plurality of non-metallictubes are coupled to a same inlet pipe, and a valve blocks a flow ofliquid from the inlet pipe into a first tube when the controller selectsa second tube for heating the liquid and does not select the first tube.19. The tankless heater of claim 18, wherein the valve is controlledbased on a signal from the controller.
 20. A heater comprising: at leastone non-metallic tube; at least one heating layer on or adjacent thetube; and a controller to generate a signal to be applied to the heatinglayer, wherein: the signal is applied through electrodes coupled to theheating layer, the heating layer generates heat in response to thesignal, said heat transferred to a gel in the tube to heat the gel towithin a first temperature range, and the heating layer is on oradjacent an external surface of the non-metallic tube and no heatingelement is included inside the non-metallic tube in contact with thegel.